The most numerous type of blood cell in healthy people. Red blood cells contain hemoglobin hemoglobin: A protein in the red blood cells. Hemoglobin picks up oxygen in the lungs and brings it to cells in all parts of the body. , a protein that picks up oxygen in the lungs and brings it to cells in all parts of the body. Also called erythrocyte erythrocyte: (i-RITH-ruh-site) See red blood cell. , RBC.
